Adwords Serving Wrong Ads

I have an ad group for 'Rackmount LCDs' and another ad group for 'Rackmount Enclosures'. Each ad group has a distinct focus, unique from each other's keywords and display ads.

In the 'Rackmount LCD' ad group, I've got "1u lcd" and "1u display" as keywords (and others). In the 'Rackmount Enclosure" ad group, I've got some other keywords with "1u" in them such as "1u chassis".

Searching Google for "1u lcd" and also "1u display" showed the ads from the 'Rackmount Enclosure' ad group instead of the intended 'Rackmount LCD' group. When people clicked these ads, (and I don't know why they did because the ad text was not appropriate) they would go to a landing page that didn't mention anything about what they searched for. They're looking for LCDs and they're seeing rackmount computers.

When I asked an Adwords phone rep about this, the answer I got was that even though I had an exact match to the search phrase, their system could arbitrarily substitute a "better performing" ad. The cure would be for me to go into each ad group and include as negative keywords all the positive keywords from the other ad groups.

To put this in perspective, say a company sells tires; bike tires and car tires and those are two keyword phrases in distinct ad groups. The ads in the Car Tires group perform well, for whatever reason. Somebody searches on "bike tires" and you display an ad for car tires because each phrase has the word "tires" in it. How is that a quality search response?

So my questions to Google are:

1. How could you say an ad from a totally wrong ad group about a subject not related to the search phrase is "better performing"?

2. What's the point of having keywords and ad groups if you randomly disregard what your advertisers want?

3. Who should know what ad to display for a search phrase and would understand that phrase better? Google or the person managing the account?

"When I asked an Adwords phone rep about this, the answer...

"When I asked an Adwords phone rep about this, the answer I got was that even though I had an exact match to the search phrase, their system could arbitrarily substitute a "better performing" ad. The cure would be for me to go into each ad group and include as negative keywords all the positive keywords from the other ad groups."

"an exact match to the search phrase" does not mean that these were exact match keywords. Any time you use phrase/broad match keywords, you risk that the wrong ad may show.

If "1u" (phrase match) is the keyword, then both '1u lcd' and '1u display' as a search query, could trigger ads to show for the 1u adgroup, depending on overall adrank.

"The cure would be for me to go into each ad group and include as negative keywords all the positive keywords from the other ad groups." Yes, that would do it, and is actually very quick and easy with the adwords editor. Perhaps a few negative broad/phrase keywords could do the trick as well.

If you really wanted to prevent this, use only exact match keywords for this structure. If those exact match to the query, exact match keywords do perform best when showing a particular ad, then make sure you have exact match adgroups to cover that. Then, add the exact negative keywords to the query campaigns/adgroups, and it shouldn't ever happen again. At least, not that I have seen for any of our accounts.